This is probably not the best way of doing this but this is what I end up doing :

Remove spaces from the field names : I replaced fields like "worth in billions", "from emerging" etc with "worth_in_billions", "from_emerging" etc in the json dataset.

Comma delimited json to newline delimited json : The json file that I had was of the form [{"_comment":"first entry" ...},{"_comment":"second entry" ...}]. But JsonLoader in Pig takes each newline to be a new entry. To make the json file newline delimited instead of comma I used js which is a command-line JSON processor. Install it using sudo apt-get install js and run cat billionaires.json | jq -c ".[]" > newBillionaires.json.

The newBillionaires.json file now has each entry on new line. Now load this file into Pig using: